1. Field of the Invention
The present invention relates to two-component developers for developing electrostatic latent images.
2. Description of Related Art
Formation of color images by the electrophotographic process generally involves the use of two-component developers that contain toner particles containing a colorant, and carrier particles for stirring and conveying the toner particles. With the spread of digital printing, for example, high-quality images and stable image formation have been increasingly required. To that end, methods have been studied from the viewpoint of energy saving, e.g., lowering the melt temperature or melt viscosity of the binder resin of toner particles for reduced energy required for the fixation of toner images on paper, reducing the amount of toner particles on paper for reduced energy required for the fixation of toner images, and so forth.
As for the latter method (i.e., reducing the amount of toner particles on paper), it has been considered to reduce the particle diameter of toner particles. By making toner particles smaller, the surface area of the toner particles is increased, and thus it becomes possible to cover paper (i.e., form an image) with a less amount of toner particles. As a result, it becomes possible to reduce energy required for the fixation without lowering image density. Further, smaller toner particles can well reproduce fine latent images, and thus achievement of both energy saving and formation of high-quality images is expected.
Examples of known two-component developers include those in which the number-average particle diameter of toner particles is specified, and those in which the number-average particle diameter and weight-average particle diameter of toner particles are specified and the shape of toner particles is specified by shape factor (see, e.g., Japanese Patent Application Laid-Open Nos. 2000-338719 and 2001-330996).